drivers/mfd/stm32-timers.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STMicroelectronics 2016
   4  * Author: Benjamin Gaignard <benjamin.gaignard@st.com>
   5  */
   6
   7 #include <linux/bitfield.h>
   8 #include <linux/mfd/stm32-timers.h>
   9 #include <linux/module.h>
  10 #include <linux/of_platform.h>
  11 #include <linux/reset.h>
  12
  13 #define STM32_TIMERS_MAX_REGISTERS      0x3fc
  14
  15 /* DIER register DMA enable bits */
  16 static const u32 stm32_timers_dier_dmaen[STM32_TIMERS_MAX_DMAS] = {
  17         TIM_DIER_CC1DE,
  18         TIM_DIER_CC2DE,
  19         TIM_DIER_CC3DE,
  20         TIM_DIER_CC4DE,
  21         TIM_DIER_UIE,
  22         TIM_DIER_TDE,
  23         TIM_DIER_COMDE
  24 };
  25
  26 static void stm32_timers_dma_done(void *p)
  27 {
  28         struct stm32_timers_dma *dma = p;
  29         struct dma_tx_state state;
  30         enum dma_status status;
  31
  32         status = dmaengine_tx_status(dma->chan, dma->chan->cookie, &state);
  33         if (status == DMA_COMPLETE)
  34                 complete(&dma->completion);
  35 }
  36
  37 /**
  38  * stm32_timers_dma_burst_read - Read from timers registers using DMA.
  39  *
  40  * Read from STM32 timers registers using DMA on a single event.
  41  * @dev: reference to stm32_timers MFD device
  42  * @buf: DMA'able destination buffer
  43  * @id: stm32_timers_dmas event identifier (ch[1..4], up, trig or com)
  44  * @reg: registers start offset for DMA to read from (like CCRx for capture)
  45  * @num_reg: number of registers to read upon each DMA request, starting @reg.
  46  * @bursts: number of bursts to read (e.g. like two for pwm period capture)
  47  * @tmo_ms: timeout (milliseconds)
  48  */
  49 int stm32_timers_dma_burst_read(struct device *dev, u32 *buf,
  50                                 enum stm32_timers_dmas id, u32 reg,
  51                                 unsigned int num_reg, unsigned int bursts,
  52                                 unsigned long tmo_ms)
  53 {
  54         struct stm32_timers *ddata = dev_get_drvdata(dev);
  55         unsigned long timeout = msecs_to_jiffies(tmo_ms);
  56         struct regmap *regmap = ddata->regmap;
  57         struct stm32_timers_dma *dma = &ddata->dma;
  58         size_t len = num_reg * bursts * sizeof(u32);
  59         struct dma_async_tx_descriptor *desc;
  60         struct dma_slave_config config;
  61         dma_cookie_t cookie;
  62         dma_addr_t dma_buf;
  63         u32 dbl, dba;
  64         long err;
  65         int ret;
  66
  67         /* Sanity check */
  68         if (id < STM32_TIMERS_DMA_CH1 || id >= STM32_TIMERS_MAX_DMAS)
  69                 return -EINVAL;
  70
  71         if (!num_reg || !bursts || reg > STM32_TIMERS_MAX_REGISTERS ||
  72             (reg + num_reg * sizeof(u32)) > STM32_TIMERS_MAX_REGISTERS)
  73                 return -EINVAL;
  74
  75         if (!dma->chans[id])
  76                 return -ENODEV;
  77         mutex_lock(&dma->lock);
  78
  79         /* Select DMA channel in use */
  80         dma->chan = dma->chans[id];
  81         dma_buf = dma_map_single(dev, buf, len, DMA_FROM_DEVICE);
  82         if (dma_mapping_error(dev, dma_buf)) {
  83                 ret = -ENOMEM;
  84                 goto unlock;
  85         }
  86
  87         /* Prepare DMA read from timer registers, using DMA burst mode */
  88         memset(&config, 0, sizeof(config));
  89         config.src_addr = (dma_addr_t)dma->phys_base + TIM_DMAR;
  90         config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
  91         ret = dmaengine_slave_config(dma->chan, &config);
  92         if (ret)
  93                 goto unmap;
  94
  95         desc = dmaengine_prep_slave_single(dma->chan, dma_buf, len,
  96                                            DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
  97         if (!desc) {
  98                 ret = -EBUSY;
  99                 goto unmap;
 100         }
 101
 102         desc->callback = stm32_timers_dma_done;
 103         desc->callback_param = dma;
 104         cookie = dmaengine_submit(desc);
 105         ret = dma_submit_error(cookie);
 106         if (ret)
 107                 goto dma_term;
 108
 109         reinit_completion(&dma->completion);
 110         dma_async_issue_pending(dma->chan);
 111
 112         /* Setup and enable timer DMA burst mode */
 113         dbl = FIELD_PREP(TIM_DCR_DBL, bursts - 1);
 114         dba = FIELD_PREP(TIM_DCR_DBA, reg >> 2);
 115         ret = regmap_write(regmap, TIM_DCR, dbl | dba);
 116         if (ret)
 117                 goto dma_term;
 118
 119         /* Clear pending flags before enabling DMA request */
 120         ret = regmap_write(regmap, TIM_SR, 0);
 121         if (ret)
 122                 goto dcr_clr;
 123
 124         ret = regmap_update_bits(regmap, TIM_DIER, stm32_timers_dier_dmaen[id],
 125                                  stm32_timers_dier_dmaen[id]);
 126         if (ret)
 127                 goto dcr_clr;
 128
 129         err = wait_for_completion_interruptible_timeout(&dma->completion,
 130                                                         timeout);
 131         if (err == 0)
 132                 ret = -ETIMEDOUT;
 133         else if (err < 0)
 134                 ret = err;
 135
 136         regmap_update_bits(regmap, TIM_DIER, stm32_timers_dier_dmaen[id], 0);
 137         regmap_write(regmap, TIM_SR, 0);
 138 dcr_clr:
 139         regmap_write(regmap, TIM_DCR, 0);
 140 dma_term:
 141         dmaengine_terminate_all(dma->chan);
 142 unmap:
 143         dma_unmap_single(dev, dma_buf, len, DMA_FROM_DEVICE);
 144 unlock:
 145         dma->chan = NULL;
 146         mutex_unlock(&dma->lock);
 147
 148         return ret;
 149 }
 150 EXPORT_SYMBOL_GPL(stm32_timers_dma_burst_read);
 151
 152 static const struct regmap_config stm32_timers_regmap_cfg = {
 153         .reg_bits = 32,
 154         .val_bits = 32,
 155         .reg_stride = sizeof(u32),
 156         .max_register = STM32_TIMERS_MAX_REGISTERS,
 157 };
 158
 159 static void stm32_timers_get_arr_size(struct stm32_timers *ddata)
 160 {
 161         /*
 162          * Only the available bits will be written so when readback
 163          * we get the maximum value of auto reload register
 164          */
 165         regmap_write(ddata->regmap, TIM_ARR, ~0L);
 166         regmap_read(ddata->regmap, TIM_ARR, &ddata->max_arr);
 167         regmap_write(ddata->regmap, TIM_ARR, 0x0);
 168 }
 169
 170 static int stm32_timers_dma_probe(struct device *dev,
 171                                    struct stm32_timers *ddata)
 172 {
 173         int i;
 174         int ret = 0;
 175         char name[4];
 176
 177         init_completion(&ddata->dma.completion);
 178         mutex_init(&ddata->dma.lock);
 179
 180         /* Optional DMA support: get valid DMA channel(s) or NULL */
 181         for (i = STM32_TIMERS_DMA_CH1; i <= STM32_TIMERS_DMA_CH4; i++) {
 182                 snprintf(name, ARRAY_SIZE(name), "ch%1d", i + 1);
 183                 ddata->dma.chans[i] = dma_request_chan(dev, name);
 184         }
 185         ddata->dma.chans[STM32_TIMERS_DMA_UP] = dma_request_chan(dev, "up");
 186         ddata->dma.chans[STM32_TIMERS_DMA_TRIG] = dma_request_chan(dev, "trig");
 187         ddata->dma.chans[STM32_TIMERS_DMA_COM] = dma_request_chan(dev, "com");
 188
 189         for (i = STM32_TIMERS_DMA_CH1; i < STM32_TIMERS_MAX_DMAS; i++) {
 190                 if (IS_ERR(ddata->dma.chans[i])) {
 191                         /* Save the first error code to return */
 192                         if (PTR_ERR(ddata->dma.chans[i]) != -ENODEV && !ret)
 193                                 ret = PTR_ERR(ddata->dma.chans[i]);
 194
 195                         ddata->dma.chans[i] = NULL;
 196                 }
 197         }
 198
 199         return ret;
 200 }
 201
 202 static void stm32_timers_dma_remove(struct device *dev,
 203                                     struct stm32_timers *ddata)
 204 {
 205         int i;
 206
 207         for (i = STM32_TIMERS_DMA_CH1; i < STM32_TIMERS_MAX_DMAS; i++)
 208                 if (ddata->dma.chans[i])
 209                         dma_release_channel(ddata->dma.chans[i]);
 210 }
 211
 212 static int stm32_timers_probe(struct platform_device *pdev)
 213 {
 214         struct device *dev = &pdev->dev;
 215         struct stm32_timers *ddata;
 216         struct resource *res;
 217         void __iomem *mmio;
 218         int ret;
 219
 220         ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
 221         if (!ddata)
 222                 return -ENOMEM;
 223
 224         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 225         mmio = devm_ioremap_resource(dev, res);
 226         if (IS_ERR(mmio))
 227                 return PTR_ERR(mmio);
 228
 229         /* Timer physical addr for DMA */
 230         ddata->dma.phys_base = res->start;
 231
 232         ddata->regmap = devm_regmap_init_mmio_clk(dev, "int", mmio,
 233                                                   &stm32_timers_regmap_cfg);
 234         if (IS_ERR(ddata->regmap))
 235                 return PTR_ERR(ddata->regmap);
 236
 237         ddata->clk = devm_clk_get(dev, NULL);
 238         if (IS_ERR(ddata->clk))
 239                 return PTR_ERR(ddata->clk);
 240
 241         stm32_timers_get_arr_size(ddata);
 242
 243         ret = stm32_timers_dma_probe(dev, ddata);
 244         if (ret) {
 245                 stm32_timers_dma_remove(dev, ddata);
 246                 return ret;
 247         }
 248
 249         platform_set_drvdata(pdev, ddata);
 250
 251         ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
 252         if (ret)
 253                 stm32_timers_dma_remove(dev, ddata);
 254
 255         return ret;
 256 }
 257
 258 static int stm32_timers_remove(struct platform_device *pdev)
 259 {
 260         struct stm32_timers *ddata = platform_get_drvdata(pdev);
 261
 262         /*
 263          * Don't use devm_ here: enfore of_platform_depopulate() happens before
 264          * DMA are released, to avoid race on DMA.
 265          */
 266         of_platform_depopulate(&pdev->dev);
 267         stm32_timers_dma_remove(&pdev->dev, ddata);
 268
 269         return 0;
 270 }
 271
 272 static const struct of_device_id stm32_timers_of_match[] = {
 273         { .compatible = "st,stm32-timers", },
 274         { /* end node */ },
 275 };
 276 MODULE_DEVICE_TABLE(of, stm32_timers_of_match);
 277
 278 static struct platform_driver stm32_timers_driver = {
 279         .probe = stm32_timers_probe,
 280         .remove = stm32_timers_remove,
 281         .driver = {
 282                 .name = "stm32-timers",
 283                 .of_match_table = stm32_timers_of_match,
 284         },
 285 };
 286 module_platform_driver(stm32_timers_driver);
 287
 288 MODULE_DESCRIPTION("STMicroelectronics STM32 Timers");
 289 MODULE_LICENSE("GPL v2");